Impeller with Hybrid Blades for Blowers

ABSTRACT

An impeller with hybrid blades can be used in any blowers, which are applied in many fields such as cooling computers and HVAC. The impeller increases air flow as well as pressure. Each hybrid blade extends from the impeller hub with the shape of an axial fan blade and smoothly transforms at a proper radius of the impeller to the shape of a centrifugal blower blade. In addition, a dual-tunnel blower with multiple outlets is also presented.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/076,701, entitled “A Dual-Tunnel Blowers,” filed on Jun. 30, 2008, which is incorporated herein by reference.

FIELD OF INVENTION

This invention relates to the field of air exchanges and more specifically to fans and blowers.

DESCRIPTION OF RELATED ART

Fans and blowers are essential components in active air exchange for many systems (e.g., electronic systems and heating, ventilating, and air conditioning systems), but their working principles and functions are different. An axial fan pumps air from inlet side to outlet side through the fan in the direction of the axis of the impeller. As a blade slices air from inlet to outlet while the impeller is rotating, air is sucked in on the inlet side and pushed out on the outlet side such that the overall air flow direction does not change. However, a centrifugal blower draws air from the inlet in the direction of the axis of the impeller and then blows the air out through the outlet that is perpendicular to the axis of the impeller. Air is drawn into the blower through the inlet side and pushed out through the side outlet by the centrifugal force provided by the impeller. Therefore, a blower changes the air flow direction and generally pumps less air than a same size axial fan.

U.S. Patent Application Publication No. 2006/0034694 by Li et al. discloses a centrifugal blower having an axial fan blade configuration. The impeller of the fan has a first set of blades on the perimeter of the impeller as in a conventional centrifugal blower. The impeller further has a second set of blades extending from the hub as in a conventional axial fan. The second set of blades is located interior to the first set of blades and the two sets of blades are separated by a constant gap. This structure of this impeller is complicated and difficult to manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an impeller with hybrid axial and centrifugal fan blades in one embodiment of the invention.

FIGS. 2 and 3A respectively illustrate unassembled and top plan views of a dual-tunnel blower with the impeller of FIG. 1 in one embodiment of the invention.

FIG. 3B illustrates the air flow pattern from the dual-tunnel blower of FIGS. 2 and 3A in on embodiment of the invention.

FIG. 4 illustrates an unassembled view of the dual-tunnel blower made with sheet metal in one embodiment of the invention.

FIG. 5 illustrates a laptop utilizing the dual-tunnel blower in one embodiment of the invention.

FIGS. 6A and 6B respectively illustrate unassembled and assembled views of a bi-directional blower with the impeller of FIG. 1 in one embodiment of the invention.

FIG. 7 illustrates an unassembled view of an asymmetrical dual-tunnel blower in one embodiment of the invention.

Use of the same reference numbers in different figures indicates similar or identical elements.

SUMMARY

In one embodiment of the invention, a hybrid blade is provided to increase the air flow volume of a blower. The hybrid blade extends from a hub with the shape of an axial fan blade and then transitions into a centrifugal fan blade. The hybrid shape of the blade allows the blower to move air into the blower using the same principle as an axial fan (by slicing the air) but expel the air to the outlets using the same principle as a blower (by centrifugal force). This hybrid mechanism increases the air flow volume as well as the pressure because the air flow is driven by air pressure generated by the axial fan portion of the rotating impeller as well as the centrifugal force generated by the centrifugal fan blade portion of the rotating impeller.

In one embodiment of the invention, a dual-tunnel blower is provided to increase the air flow as well as the pressure. The dual-tunnel blower is composed of an inlet on the top or the bottom side of the blower, an impeller with axial fan blades or the hybrid blades previously described, and a housing with two partitions that divide the housing into two airflow tunnels with multiple outlets.

DETAILED DESCRIPTION

FIG. 1 illustrates an impeller 100 with hybrid blades that combine the blade designs of axial fans and blowers in order to increase the air flow volume and the pressure produced by a blower in one embodiment of the invention. Impeller 100 can be used in many types of blowers.

Impeller 100 includes a hub 102 and blades 104 (only one is labeled for clarity) that extend from the hub. Hub 102 defines a mounting hole 106 for attaching hub 102 to the axel of a motor. Alternatively, hole 106 is mounted to a drive axle that is linked by belt, chain, or gears to a motor. Blades 104 are backward curved relative to a counterclockwise rotation 108. In other embodiments, blades 104 are forward curved or radial relative to rotation direction 108. Each blade 104 includes an axial fan blade portion 110 that extends from hub 102 to a radius R indicated by a phantom arc 112, and a centrifugal fan blade portion 114 that continues from radius R to the blade edge at the tip of the blade. Note that radius R is determined from the rotational axis of impeller 100.

Axial fan blade portion 110 has a fixed or variable blade angle where the variable blade angle can twist at a fixed or variable rate. Axial fan blade portion 110 allows blades 104 to move the air into a fan by slicing the air as in conventional axial fan. Axial fan blade portion 110 may have fixed or variable cross-sections. The cross-section may have the shape of a rectangle, an airfoil, or another shape that provides sufficient mechanical stiffness to minimize vibration and noise.

Centrifugal fan blade portion 114 has a variable blade angle that transitions from the blade angle of axial fan blade portion 110 to the blade edge that is substantially vertical relative to the plane of rotation of impeller 100 (e.g., having a blade angle from 0 to 10 degrees). This allows blades 104 to regulate the air out of a fan by centrifugal forces as in conventional blowers. Centrifugal fan blade portion 114 may have fixed or variable cross-sections. The cross-section may have the shape of a rectangle, an airfoil, or another shape that provides sufficient mechanical stiffness to minimize vibration and noise.

FIGS. 2 and 3A illustrate a dual-tunnel blower 200 utilizing impeller 100 in one embodiment of the invention. Although impeller 100 is used, conventional impellers for fans and blowers may be used in other embodiments.

Blower 200 includes a housing 202 that receives impeller 100, and a top cover 204 that mounts atop the housing. Impeller 100 is directly attached or indirectly linked to a motor, which may be located inside or outside of housing 202. Cover 204 has screw holes for fixing the cover to housing 202. Housing 202 also has screw holes for fixing blower 200 to another system. An air inlet 205 to impeller 100 can be defined on cover 204 as shown, or on the bottom of housing 202.

Housing 202 is generally rectangular with vertical sidewalls 206 and 208 on two opposing sides. The opposing openings between sidewalls 206 and 208 form air outlets 210 and 212. Sidewall 206 includes a partition 214 near air outlet 210. Partition 214 protrudes from the end of sidewall 206 and forms a substantially vertical edge at a small distance from the blade edges. From its edge, partition 214 can optionally maintain a uniform gap to the blade edges for greater than the distance between two adjacent blade edges before tapering back to sidewall 206.

Diametrically opposed to partition 214, sidewall 208 includes a partition 216 near air outlet 212. Partition 216 protrudes from the end of sidewall 208 and forms a substantially vertical edge at a small distance from the blade edges. From its edge, partition 216 can optionally maintain a uniform gap to the blade edges for greater than the distance between two adjacent blade edges before tapering back to sidewall 208.

Partitions 214 and 216 divide blower 200 into two tunnels and prevent the air in the two tunnels from substantially mixing. A first tunnel is formed between a first portion 205A (FIG. 3A) of air inlet 205 and air outlet 210. A second tunnel is formed between a second portion 205B (FIG. 3A) of air inlet 205 and air outlet 212. The first and the second portions of air inlet 205 are demarcated by an imaginary line that passes from the protruding edge of partitions 214 to hub 102 (more specifically to the rotational axis of impeller 100), and from the hub to the protruding edge of partition 216. The protruding edge of partition 214 defines the end of the first tunnel and the beginning of the second tunnel. Similarly, the protruding edge of partition 216 defines the end of the second tunnel and the beginning of the first tunnel.

As blades 104 rotate counterclockwise, axial fan blade portions 110 of the blades move the air into blower 200 by slicing the air as in a conventional axial fan, and centrifugal fan blade portions 114 of the blades move the air out of blower 200 by centrifugal forces as in a conventional blower. As air is pushed out through outlets 210 and 212 by the centrifugal force and the air pressure supplied by the rotating impeller, the air density is lowered in the space between adjacent blades 104 past the protruding edges of partitions 214 and 216. As blades 104 rotate past partitions 214 and 216, the “negative pressure” difference between the ambient air pressure and the space between adjacent blades 104 draws air from air inlet 205 into the space between the adjacent blades.

In air outlet 210, housing 202 includes stationary airfoils 218 and 220. Similarly in air outlet 212, housing 202 includes stationary airfoils 222 and 224. The placement and the shape of the stationary airfoils provide the desired air flow distribution and air flow direction. For example, the stationary airfoils may ensure that the air exiting through the air outlets is evenly distributed across each outlet. This improves the cooling of any heat sink placed next to the outlet. Furthermore, the stationary airfoils may regulate the air flow so the air exits perpendicular to the air outlets. This prevents the air from vibrating the fins of the heat sink and generating noise since turbulent flow is minimized. The exact placement and shape of the stationary airfoils can be calculated through computational fluid dynamics.

Referring to FIG. 3B, as air is pushed out through air outlets 210 and 212 by centrifugal force and the air pressure supplied by the impeller, the air density is lowered in the space between adjacent blades 104 when the blades rotate past the protruding edges of partitions 214 and 216 so that the “negative pressure” difference between the ambient air pressure and the space between the adjacent blades draws air from outside of blower 200 into the space between the adjacent blades. Thus, air inlet 205 in cover 204 (shown as a phantom line) should provide a larger area past each protruding edge to allow more air to be sucked into the space between adjacent blades 104. However, air inlet 205 should also prevent the air from escaping back out through the inlet.

To meet the above goals, the boundary of air inlet 205 is generally in the shape of a curvilinear loop that curves inward and outward at specific points from the rotational axis of impeller 100. Near the start of the first tunnel after partition 216, the distance from the boundary to the impeller axis is the radius of impeller 100. The distance gradually and smoothly decreases to less than the impeller radius (e.g., radius R at the transition point between axial fan blade and centrifugal fan blade portions) near the end of the first tunnel before partition 214. The distance then gradually and smoothly increases to the impeller radius near the start of the second tunnel after partition 214. The distance gradually and smoothly decreases to radius R near the end of the second tunnel before partition 216. The distance then gradually and smoothly increases to the impeller radius near the start of the first tunnel after partition 216.

The increase of the distance from the impeller axis to the boundary near the start of each tunnel allows the “negative pressure” in the space between adjacent blades 104 to draw in more air from outside of blower 200. The decrease in the distance between the start and the end of each tunnel allows cover 204 to overlap the blade edges and prevent the air from escaping back through inlet 205.

Experiments have shown that each air tunnel of blower 200 pumps the same or more air than a conventional blower that is the same size as blower 200. Thus, a single blower 200 may be used to replace two conventional blowers.

FIG. 4 illustrates blower 200 as being made from sheet metal instead of being injection molded plastic as in FIGS. 2 and 3A. Same or similar elements are identified by the same reference numbers. Other methods for making blower 200 without deviating from its principles are within the capabilities of those skilled in the art.

FIG. 5 illustrates a form factor of a laptop computer 500 with blower 200 in one embodiment of the invention. Laptop 500 includes a system case 502 with additional components, such as the display, the keyboard, the optical drive, the battery, the track pad, and various ports, that are omitted in order to better illustrate the thermal paths in the laptop. Blower 200 is located in case 502 where a vent in the case above blower 200 allows it to draw in cool ambient air.

A heat pipe 504 is mounted above and thermally coupled to a central processing unit (CPU) (not visible) on a printed circuit board (PCB) 506. Heat pipe 504 carries heat from the CPU to a heat sink 508. Heat sink 508 has its fins located between air outlet 212 (not labeled) of blower 200 and a vent 510 on the side of case 502. This allows blower 200 to blow cool air through the fins of heat sink 508 and out through vent 510 to carry away the heat generated by the CPU.

A duct 512 couples air outlet 210 (not labeled) of blower 200 to a heat sink 514, which is mounted above and thermally coupled to a graphical processing unit (GPU) (not visible) on PCB 506. This allows blower 200 to blow cool air through the fins of heat sink 514 and out through a vent 516 located on the side of case 502 to carry away the heat generated by the GPU. Note that the locations of the GPU and the CPU can be reversed, and the heat sinks may be used to cool other heat sources within laptop 500. Furthermore, duct 512 may be optional depending on the layout and the thermal design of laptop 500.

The configuration of laptop 500 with blower 200 offers several advantages. Typically a conventional blower sucks in the hot air inside a laptop and moves it out of the laptop. This requires a gap between the inlet surface of the blower and the opposing laptop surface (typically the top of the blower and the laptop cover) so the hot air can enter the blower. The configuration above uses blower 200 to suck in cool air and blow it into the laptop to cool components therein. Thus, a gap is not needed between the inlet surface of blower 200 and the opposing laptop surface. Furthermore, two streams of cool air are provided to cool multiple components inside the laptop.

FIGS. 6A and 6B show a bi-directional blower 600 with impeller 100 in one embodiment of the invention. Bi-direction blower 600 can be implemented like any embodiments of the bi-directional blower described in U.S. Pat. No. 7,255,532 by the present inventor.

Blower 600 includes a housing 602 that receives impeller 100, and a top cover 604 that mounts atop the housing. Cover 604 has screw holes for fixing the cover to housing 602. Housing 602 also has screw holes for fixing blower 600 to another system. A first air inlet 605 to impeller 100 can be defined on cover 604 as shown, or on the bottom of housing 602.

Housing 602 is generally rectangular with vertical sidewalls 606 and 608 on two opposing sides. Opposing openings between sidewalls 606 and 608 form a first air outlet 610 and a second air inlet 611. An opening on sidewall 608 forms a second air outlet 612.

Sidewall 606 includes a partition 614 between first air outlet 610 and second air inlet 611. Sidewall 608 includes a partition 616 between second air outlet 612 and first air outlet 610. Partitions 614 and 616 protrude from their respective sidewalls toward the blade edges and maintain a small uniform gap to the blade edges for greater than the distance between two adjacent blade edges before tapering back to their respective sidewalls. Partitions 614 and 616 divide blower 600 into a first air channel from first air inlet 605 to first air outlet 610, and a second air channel from second air inlet 611 to second air outlet 612. As partitions 614 and 616 have widths longer than the distance between two adjacent blade edges, they prevent the air in the two air channels from mixing. In air outlet 610, housing 602 includes stationary airfoils 620 (only one is labeled for clarity).

The functions of the components of blower 600 are not explained as they function in substantially the same manner as the corresponding components in the embodiments described above and in the bidirectional blower in U.S. Pat. No. 7,255,532 by the present inventor.

FIG. 7 illustrates an asymmetrical dual-tunnel blower 700 in one embodiment of the invention. Blower 700 is similar to blower 200 but with an asymmetrical arrangement of the sidewalls, partitions, and outlets.

Blower 700 includes a housing 702 that receives impeller 100, and a top cover 704 that mounts atop the housing. Cover 704 has screw holes for fixing the cover to housing 702. Housing 702 also has screw holes for fixing blower 700 to another system. An air inlet 704 can be defined on cover 702 or on the bottom of housing 702.

Housing 702 has four sides. A sidewall 706 is formed along one side, and a sidewall 708 is formed along one opposing side and one adjacent side. The openings between sidewalls 706 and 708 form air outlets 710 and 712. Sidewall 706 includes a partition 714 near the end of air outlet 710. Partition 714 protrudes from the end of sidewall 706 and forms a substantially vertical edge at a small distance from the blade tips. From its edge, partition 714 can optionally maintain a uniform gap to the blade edges for greater than the distance between two adjacent blade edges before tapering back to sidewall 706 near the start of air outlet 712.

Similarly, sidewall 708 includes a partition 716 near the end of air outlet 712. Partition 716 protrudes from the end of sidewall 708 and forms a substantially vertical edge at a small distance from the blade edges. From its edge, partition 716 can optionally maintains a small uniform gap to the blade edges for greater than the distance between two adjacent blade edges before tapering back to sidewall 708.

Partitions 714 and 716 divide blower 700 into two tunnels and prevent the air in the two tunnels from substantially mixing. A first tunnel is formed between a first portion of air inlet 705 and air outlet 710. A second tunnel is formed between a second portion of air inlet 705 and air outlet 712. The first and the second portions of air inlet 705 are demarcated by an imaginary line that passes from the protruding edge of partitions 714 to hub 102 (more specifically to the rotational axis of impeller 100), and from the hub to the protruding edge of partition 716. The protruding edge of partition 714 defines the end of the first tunnel and the beginning of the second tunnel. Similarly, the protruding edge of partition 716 defines the end of the second tunnel and the beginning of the first tunnel.

In air outlet 710, housing 702 includes stationary airfoils 718 and 720. In air outlet 712, housing 702 includes a mounting hole structure 722 that provides the mounting hole for the housing and cover 704.

The boundary of air inlet 705 in cover 704 is generally in the shape of a curvilinear loop that curves inward and outward at specific points from the rotational axis of impeller 100. Near the start of the first tunnel after partition 716, the distance from the boundary to the impeller axis is the radius of impeller 100. The distance gradually and smoothly decreases to less than the impeller radius (e.g., radius R at the transition point between axial fan blade and centrifugal fan blade portions) near the end of the first tunnel before partition 714. The distance then gradually and smoothly increases to the impeller radius near the start of the second tunnel after partition 714. The distance gradually and smoothly decreases to radius R near the end of the second tunnel before partition 716. The distance then gradually and smoothly increases to the impeller radius near the start of the first tunnel after partition 716.

The functions of the components of blower 700 are not explained as they function in substantially the same manner as the corresponding components of blower 200.

Various other adaptations and combinations of features of the embodiments disclosed are within the scope of the invention. For example, a blower similar to blower 200 can be made with one of the air outlet replaced with a sidewall so the resulting blower has a single air outlet. Furthermore, the impeller with the hybrid blades can be used in blowers for many applications, including HVAC (heating, ventilating, and air conditioning) applications. Numerous embodiments are encompassed by the following claims. 

1. An impeller for a blower, comprising: a hub; and blades extending from the hub, each blade comprising: a first portion comprising an axial fan blade from the hub to a radius R; and a second portion comprising a centrifugal fan blade from the radius R to a blade edge at a blade tip, each blade edge being substantially vertical relative to a plane of rotation of the impeller, the radius R being a transition point from the first portion to the second portion.
 2. The impeller of claim 1, wherein: the first portion has a fixed blade angle; and the second portion having a variable blade angle.
 3. The impeller of claim 2, wherein each blade is backward curved, forward curved, or radial relative to a rotation of the impeller.
 4. A blower, comprising: a motor; a impeller attached or linked to the motor, the impeller comprising: a hub; and blades extending from the hub; a housing receiving the impeller, the housing comprising first and second sidewalls that define first and second air outlets, wherein: the first sidewall comprises a first partition with a first partition edge adjacent to the first air outlet, the first partition edge protruding close to blade edges; and the second sidewall comprises a second partition with a second partition edge adjacent to the second air outlet, the second partition edge protruding close to the blade edges; a cover on the housing; an air inlet defined on the cover or the bottom of the housing; wherein the first and the second partitions divide the blower into first and second tunnels, the first tunnel being from a first portion of the air inlet to the first air outlet, the second tunnel being from a second portion of the air inlet to the second air outlet, the first partition edge defining the end of the first tunnel and the start of the second tunnel, the second partition edge defining the end of the second tunnel and the beginning of the first tunnel.
 5. The blower of claim 4, wherein each blade comprises: a first portion comprising an axial fan blade from the hub to a radius R; and a second portion comprising a centrifugal fan blade from the radius R to a blade edge of a blade tip, each blade edge being substantially vertical relative to a plane of rotation of the impeller, the radius R being a transition point from the first portion to the second portion.
 6. The impeller of claim 5, wherein: the first portion has a fixed blade angle; and the second portion having a variable blade angle.
 7. The impeller of claim 6, wherein each blade is backward curved, forward curved, or radial relative to a rotation of the impeller.
 8. The blower of claim 4, wherein each of the first and the second partitions maintains a constant gap to the blade edges for a distance greater than the distance between two consecutive blade edges.
 9. The blower of claim 4, wherein the first and the second sidewalls are formed along two opposing sides of the housing.
 10. The blower of claim 4, wherein one of the first and the second sidewalls is formed along at least two sides of the housing.
 11. The blower of claim 4, wherein the air inlet is divided into the first and the second portions along a line that passes from the first partition edge to the hub, and from the hub to the second partition edge.
 12. The blower of claim 4, wherein the housing further comprises at least one airfoil in at least one of the first and the second air outlets.
 13. The blower of claim 4, wherein the boundary of the air inlet is a curvilinear loop, the distance from the boundary to the rotational axis of the impeller is approximately equal to the radius of the impeller near the start of each tunnel and decreases to less than the radius of the impeller near the end of each tunnel, and the boundary comprises smooth curves that join the portions of the boundary near the start and the end of the first and the second tunnels.
 14. The blower of claim 5, wherein the boundary of the air inlet is a curvilinear loop, the distance from the boundary to the rotational axis of the impeller is approximately equal to the radius of the impeller near the start of each tunnel and decreases to less than the radius of the impeller near the end of each tunnel, and the boundary comprises smooth curves that join the portions of the boundary near the start and the end of the first and the second tunnels. 